Review: HP DreamColor Z27x Display

By David English
/ December 18, 2014

If you work with video content, you probably spend much of your time staring at a desktop monitor. And you probably wonder if what you see on the screen is an accurate representation of what your content will look like as a finished product. You could always throw money at the problem, but most of us can’t afford to pay $20,000 to $30,000 for a color-accurate monitor. What many post-production facilities want is a video-optimized monitor that costs a fraction of that price.

That’s the niche that HP hopes to fill with its new $1,499 HP DreamColor Z27x display. An upgrade to the original DreamColor display that was introduced back in 2008, it costs less than half the price of the original, yet it has three times the color accuracy. HP worked closely with DreamWorks and one of the top VFX houses (HP won’t say which one) when designing this product. As a result, it includes many of the features that postproduction companies have requested over the years.

This monitor has a 27-inch second-generation IPS panel with a 2560×1440 resolution. It comes with push-button access for the sRGB D65, sRGB D50, AdobeRGB, BT.709, BT.2020, DCI-P3, and native color spaces, though you can program any of the seven presets to suit your own requirements. The output is true 10-bit color for 1.07 billion colors. The colors are calculated with 14-bit precision, and it can produce 1,024 gray levels per channel. There’s input support for 4K video for both 4096×2160 and 3840×2160, even though those resolutions are higher than the panel can technically display. It has a 7 ms response time (gray to gray). And there’s a built-in calibration engine that’s compatible with some of the color measurement instruments that are often used to calibrate DCI projectors.

Hue Do You Trust
The Z27x covers 100 percent of the sRGB and AdobeRGB color gamuts, as well as 98.8 percent of the DCI-P3 color gamut. Why not 100 percent of DCI-P3? It’s very difficult to precisely nail the DCI primaries on an LCD monitor. With LCD panels, the greens tend to be overly saturated. Manufacturers can use filters to pull back the greens, but those filters tend to leak blue. Then, when the user pushes the image, the blue primary can become unstable and start to drift.

According to Greg Staten, HP’s DreamColor product manager, the Z27X was designed specifically to be used as a studio monitor. “It’s literally the best DCI coverage that you’ll find out there unless you spend around $30,000 for your display,” he said. While I don’t have the equipment or expertise to properly evaluate compliance with the DCI color spec, I can tell you that I saw a subtlety in the colors and shading, especially in the shadows, that I haven’t seen on a display that sells for anywhere close to this price.

The color accuracy is particularly impressive in two areas that have been problematic for computer monitors. Those areas are neutral grayscales and low-luminance performance. You might not think that a monitor’s grays would be especially important in a world where almost all new content is captured and presented in color. However, if the core grays aren’t neutral, the chromatic grays and many of the shadow areas will seem off. Inexpensive monitors will generally try to cover the primary colors and not worry about the rest. I used the Z27x to view uncompressed photos from a Leica M Monochrom camera, as well as Blu-ray discs of classic black-and-white Hollywood films (including The Grapes of Wrath, Touch of Evil, and The Big Combo), and saw no color tint or fringing in the monochrome content.

Similarly, there will often be significant shifts in color with inexpensive monitors when you turn down the luminance levels. The Z27x can go down as low as 48 cd/m2 (candelas per square meter), which is not unusual. The trick is to go that dim without having the colors become unstable. There were no color shifts or significant changes in contrast as I lowered the luminance setting on the monitor. HP engineered the backlight so that this monitor is extremely stable, even at low light levels. That’s especially important for use with digital cinema applications. The Z27x calibrates its DCI setting to 48 cd/m2, which is the SMPTE standard for cinema light.

HP has also given special care to see that the color and contrast remain as stable as possible when the screen is viewed from an oblique angle. That’s expected for left- and right-angle viewing. However, this particular monitor excels in maintaining a consistent image even when viewed at extreme angles from above or below. It’s rated at 178 degrees for both horizontal and vertical viewing angles. For facilities where a manager or client may sometimes view a project alongside the content creator or editor, this could be a big plus. Too often, we’re unaware of how different the video might look to another viewer who is standing at a different angle to the screen.

If you’re shopping for an LCD monitor, and you dig into the specs for the various displays, you’ll notice that the IPS panels have a typical 1000-to-1 (or 1000:1) contrast ratio. That means that a batch of the displays will have an average 1000-to-1 contrast ratio. An individual display might be as low as 600-to-1 and still be within that typical 1000-to-1 spec. For the Z27x, HP has taken the unusual step of guaranteeing a minimum 800-to-1 contrast ratio. That might seem like a step backwards, but it means that HP has to pay extra for its panels so that it can send back any individual panels that fall below the 800-to-1 threshold. It sets a floor for the contrast level that other manufacturers haven’t yet been willing to guarantee.

It’s worth pointing out that the rated 7 millisecond response time for the Z27x is a typical rating with no guaranteed minimum. So it’s possible, as with other monitors rated with a typical response time, that you may receive a higher or lower result, based on whatever panels the component manufacturer happens to supply HP on that day.

To further evaluate the Z27x, I used DisplayMate for Windows to adjust the monitor to its optimal settings. I then ran the program’s test procedures to check the monitor’s geometry, distortion, sharpness, and resolution, as well as its color and grayscale capabilities. I found no abnormalities, errors, or artifacts with any of the test grids. I was especially impressed with the grayscale results. All of the incremental 64-step gray boxes were visible with no color tinting or fringing. Colors were accurately displayed throughout the various tests.

When in Doubt
As you would expect from a professional-quality monitor, the Z27x is calibration friendly. However, this monitor is different in that the calibration engine is fully internal and optimized for DCI. One of the advantages to having an integrated calibration engine is you don’t need a computer to calibrate the display. You can use HP’s optional HP DreamColor Calibration Solution ($250), which plugs into one of the onboard USB connectors. The calibration engine is also compatible with third-party color measurement instruments, including the Klein Instruments K10-A, Konica Minolta CA-310, and Photo Research spectroradiometers. These are high-end devices that are commonly used in large animation studios and major VFX houses to calibrate their screening and dailies rooms. Now they’ll be able to use the same instruments with their desktop monitors that they use with their other display devices. The Klein K10-A costs about $7,000, while the Photo Research instruments can go as high as $50,000 to $70,000.

According to HP, the internal calibration engine—using either color checker patterns or saturation sweeps—has a Delta E color accuracy rating of around 0.5. The Delta E standard takes into consideration both the hue and saturation of the colors. A Delta E rating of 2.6 is considered to be the point at which a typical human eye cannot see a difference between two colors. A trained colorist might see differences down to a Delta E rating of 1.0 to 1.5. A Delta E rating of 1.0 is considered to be the limit of what any human eye can physically discern.

Another advantage to having an internal calibration engine is the possibility of running customized scripts. The entire calibration routine can be scripted using XML. You write an XML script, put it on a USB thumb drive, and plug it into one of the designated DreamColor USB ports. Why would you want to automate the calibration process if it’s based on an absolute standard? A post or VFX supervisor may have a preference that’s particular to the work environment. For example, the Z27x calibrates the BT.709 spec for 100 cd/m2, but some facilities may prefer their BT.709 to be set at 70, 85, or even 110 cd/m2.

Being able to calibrate your desktop monitors to your DCI projector using the same calibration device, and being able to sync that calibration to match any in-house preferences for established light levels, could be key features for many postproduction facilities. Those features haven’t been available previously in a monitor that companies could afford to place at every workstation.

Make-Do 4K
The Z27x has rather extensive support for 4K video, despite its less-than-4K resolution. Because of its color accuracy, you might use it to preview and color check your 4K video, at least until you can afford a fully color-accurate 4K monitor. One of the 4K viewing modes scales down the 4K image to the monitor’s native 2560×1440 resolution using a scaling algorithm that attempts to reduce the image with minimal distortion. The algorithm doesn’t use edge sharpening, noise reduction, or other enhancements that are typically found in a scaling function. I was pleased to find that even with the lower resolution, onscreen 4K text was quite readable, in most cases.

There are also two pixel-for-pixel viewing modes that maintain the full 4096×2160 or 3840×2160 aperture. One of the options is a 4K scroll mode. After selecting the scroll mode, a pop-up appears with an outline box indicating the current area of interest. You can scroll through your 4K content using the top four buttons on the bezel. The four buttons function as up, down, left, and right navigation tools. The other option is a four-corners viewing mode. Here you push a single button to shift the frame. With each button press, it cycles through the upper left-hand corner, upper right-hand corner, lower left-hand corner, lower right-hand corner, and center view.

The 4K viewing modes are designed to work with the monitor’s aspect ratio management system. For example, if you choose 2.39:1 as your onscreen aspect ratio, you can then view the 4K image as center, left, or right. Because this is a wide aspect ratio, you can view your 2.39:1 4K video with a three-step push-button cycle as opposed to the default five-step cycle.

When I spoke with Staten, he mentioned how the Z27x might also be used for 4K production work. He said that one of the beta testers was a DP who used the monitors for framing and focus. Each monitor functioned much like a live 27-inch viewfinder. According to Staten, the DP had them hooked up to his A and B cameras, and he used the 4K scaling mode to help compose the shot and correct the lighting. Then if he needed to check the focus, or look at a detail, he switched from the whole-image view to one of the pixel-for-pixel views. The crew also used the Z27x for viewing dailies, because they didn’t have a DCI projector on location.

Conclusion
The HP DreamColor Z27x packs a lot into a $1,499 studio monitor. Unless you’re willing to pay six figures for your new monitor, it’s currently the best option for critical color work. And it’s chock full of the kinds of features that a large animation studio or VFX house would want. That includes the low purchase price, because even large, successful companies will balk at a lofty price tag when it comes to equipping hundreds of desktops with a color-accurate monitor.

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Summary: Don’t want to pay $20,000 or more for a color-critical monitor? This $1,499 second-generation DreamColor display covers 98.8 percent of the DCI-P3 color gamut, as well as 100-percent of sRGB and AdobeRGB. Plus, it has many features designed specifically for postproduction facilities.

What’s Missing: It doesn’t quite cover the full DCI-P3 color gamut, though you’ll have to pay considerably more to get that remaining 1.2 percent of coverage. The 7 millisecond response rate is less impressive than the other specs.